Cognitive radio is a promising solution in improving spectrum utilization efficiency by allowing unlicensed users to access idle licensed spectrum opportunistically. Cognitive Radio Cognitive Network (CRCN) supports multi-interface multi-channel functions in Network Simulator 2 (NS-2). However, CRCN only supports cognitive functions to two MAC protocols that is Macng and Maccoon. Both MACs were designed along with CRCN. Existing MAC protocols such as Simple MAC and 802.11 does not support cognitive function. In this paper, modifications were made to support multi-interface multichannel function and primary user recognition in 802.11 MAC coding. Simulation was run to compare the performance of different cognitive MACs: Simple MAC, 802.11, and Macng, in smart grid communications. The performance metric used was average delay. Simulation results showed that cognitive radio outperforms non-cognitive radio. In addition, cognitive 802.11 has better delay performance than Simple MAC and Macng. This indicates that choice of cognitive MAC protocols affect the performance of smart grid communications.